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Environmental

Fact Sheet

 Printed on Recycled Paper

United States

Environmental Protection

Agency

Air and Radiation EPA420-F-01-030

September 2001

Office of Transportation and Air Quality

Frequently Asked Questions:

Environmental Impacts of

Recreational Vehicles and

Other Nonroad Engines

In September 2001, the U.S. Environmental Protection Agency (EPA)

published a Notice of Proposed Rulemaking (NPRM) seeking public

comment on our plan to set emission control standards for recreational

and other nonroad vehicles. This information sheet addresses common

questions about the environmental impacts of this proposal.

What vehicles and engines are covered in this

proposal?

We are proposing new emission control standards for three groups of

previously unregulated nonroad engines and vehicles that cause or

contribute to air pollution:

ï Large Industrial SI Engines: Spark-ignition nonroad engines rated

over 25 horsepower (19 kW) used in commercial and industrial

applications, including forklifts, electric generators, airport baggage

transport vehicles, and a variety of other construction, farm, and

industrial equipment.

ï Recreational Vehicles: Spark-ignition nonroad engines used in offhighway motorcycles, all-terrain-vehicles (ATVs), and snowmobiles.

ï Diesel Marine Engines: Diesel engines rated at or above 50 horsepower (37 kW) used in recreational boats.
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How do these engines and vehicles affect air quality?

Nationwide, these engines and vehicles are a significant source of mobile-source air pollution. In 2000, they accounted for about 13 percent of

national mobile-source hydrocarbon (HC) emissions, 6 percent of mobile-source carbon monoxide (CO) emissions, 3 percent of mobile-source

oxides of nitrogen (NOx) emissions, and 1 percent of mobile-source

particulate matter (PM) emissions. Recreational vehicles by themselves

account for nearly 10 percent of national mobile-source HC emissions

and about 3 percent of national mobile-source CO emissions. If left

uncontrolled, these engines will contribute 33 percent of national mobile

source HC emissions, 9 percent of CO emissions, 9 percent of NOx

emissions, and 2 percent of PM emissions in 2020.

On an individual basis, these vehicles can have very high emission rates.

This is illustrated in the figure below, which shows that a two-stroke

ATV or motorcycle can emit as much pollution in one hour as over 30

automobiles operating for one hour. Similarly, a snowmobile can emit as

much as nearly 100 automobiles.

What are the human health and welfare effects of

these pollutants?

The engines that are covered by this proposal contribute to ozone formation and ambient PM and CO levels. These pollutants are subject to our

National Ambient Air Quality Standards (NAAQS), and states that

exceed NAAQS levels are required to take measures to reduce emissions.

In addition, these engines also emit Mobile Source Air Toxics.
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ï Ozone. Ground-level ozone, the main ingredient in smog, is

formed by complex chemical reactions of volatile organic compounds (VOC) and NOx in the presence of heat and sunlight.

Ozone forms readily in the lower atmosphere, usually during hot

summer weather. Volatile organic compounds are emitted from a

variety of sources, including motor vehicles, chemical plants,

refineries, factories, consumer and commercial products, and

other industrial sources. Volatile organic compounds also are

emitted by natural sources such as vegetation. Oxides of nitrogen

are emitted largely from motor vehicles, off-highway equipment,

power plants, and other sources of combustion. Hydrocarbons

(HC) are a large subset of VOC, and to reduce mobile source

VOC levels we set maximum emissions limits for hydrocarbon as

well as particulate matter emissions.

Elevated ozone concentrations remain a serious public health

concern throughout the nation. In 1999, 90.8 million people lived

in 31 areas designated nonattainment under the 1-hour ozone

NAAQS. Increases in ozone concentrations in the air have been

associated with increases in hospitalization for respiratory causes

for individuals with asthma, worsening of symptoms, decrements

in lung function, and increased medication use, and chronic

exposure may cause permanent lung damage. The risk of suffering these effects is particularly high for children and for people

with compromised respiratory systems. There is strong and

convincing evidence that exposure to ozone is associated with

exacerbation of asthma-related symptoms.

ï Carbon Monoxide. Carbon monoxide (CO) is a colorless, odorless gas produced through the incomplete combustion of carbonbased fuels. Carbon monoxide enters the bloodstream through the

lungs and reduces the delivery of oxygen to the bodyís organs and

tissues. The health threat from CO is most serious for those who

suffer from cardiovascular disease, particularly those with angina

or peripheral vascular disease. Healthy individuals also are

affected, but only at higher CO levels. Exposure to elevated CO

levels is associated with impairment of visual perception, work

capacity, manual dexterity, learning ability and performance of

complex tasks.
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In 1999, 30.5 million people lived in 17 areas designated nonattainment under the CO NAAQS. High concentrations of CO

generally occur in areas with elevated mobile-source emissions.

Peak concentrations typically occur during the colder months of

the year when mobile-source CO emissions are greater and

nighttime inversion conditions are more frequent. Snowmobiles,

which have relatively high per engine CO emissions, contribute

to ambient CO levels in CO nonattainment areas.

ï Particulate Matter. Particulate matter represents a broad class of

chemically and physically diverse substances. It can be principally characterized as discrete particles that exist in the condensed (liquid or solid) phase spanning several orders of magnitude in size. All particles equal to and less than 10 microns are

called PM10. Fine particles can be generally defined as those

particles with an aerodynamic diameter of 2.5 microns or less

(also known as PM2.5), and coarse fraction particles are those

particles with an aerodynamic diameter greater than 2.5 microns,

but equal to or less than a nominal 10 microns.

Particulate matter, like ozone, has been linked to a range of

serious respiratory health problems, including premature mortality, aggravation of respiratory and cardiovascular disease (as

indicated by increased hospital admissions and emergency room

visits, school absences, work loss days, and restricted activity

days), aggravated asthma, acute respiratory symptoms, including

aggravated coughing and difficult or painful breathing, chronic

bronchitis, and decreased lung function that can be experienced

as shortness of breath.

The most recent PM10 monitoring data indicate that 14 designated

PM10 nonattainment areas with a population of 23 million violated the PM10 NAAQS in the period 1997-99. In addition, there

are 25 unclassifiable areas that have recently recorded ambient

concentrations of PM10 above the PM10 NAAQS. According to

our national modeled predictions, there were a total of 76 million

people (1996 population) living in areas with modeled annual

average PM2.5 concentrations at or above 16 μg/m3 (29 percent of

the population), a level that is associated with harmful human

health effects, including premature mortality.
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Sources contribute to ambient PM levels directly, through PM in

their emissions, and indirectly, through their emissions of organic

carbon, especially NOx and SOx. Organic carbon accounts for

between 27 and 36 percent of fine particle mass depending on the

area of the country. Secondary PM is dominated by sulfate in the

eastern U.S. and nitrate in the western U.S. The vast majority

(>90 percent) of the direct mobile source PM emissions are in the

fine PM size range.

ï Air Toxics. Emissions from the engines covered by this proposal

also contain several Mobile Source Air Toxics, including benzene, 1,3-butadiene, formaldehyde, acetaldehyde, and acrolein.

Users of these engines and vehicles can experience high levels of

personal exposure to these substances. For example, snowmobile

riders and those directly exposed to snowmobile exhaust emissions can be exposed to benzene levels two to three orders of

magnitude greater than the 1996 national average benzene

concentrations. These elevated levels are also known as air toxic

ìhot spots,î which are of particular concern to EPA.

ï Visibility. Fine PM is the major cause of reduced visibility in

parts of the United States, including many of our national parks.

In particular, HC emissions from snowmobiles in the winter

months can contribute significantly to the organic carbon fraction

of fine particles which are largely responsible for visibility

impairment. In Yellowstone National Park, a park with high

snowmobile usage during the winter months, snowmobile HC

emissions can exceed 500 tons per year, as much as several large

stationary sources, and account for nearly 65 percent of annual

HC emissions in the park.

How would the proposed standards affect emissions

and air quality?

When the proposed emission standards for Large SI, recreational engines, and marine diesel engines are fully implemented in 2020, we

expect a 70 percent reduction in HC emissions from these engines, a 75

percent reduction in NOx emissions, and a 56 percent reduction in CO

emissions. These emission reductions will help reduce ambient concentrations of ozone, CO, and fine PM. In addition, they will reduce personal exposure for people who operate or who work with or are otherwise in close proximity to these engines and vehicles. They will also

improve visibility in national parks.
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For More Information:

See Chapter 1, Health and Welfare Concerns, of the Draft Regulatory

Support Document for this proposal. That document can be found on our

website: http://www.epa.gov/otaq/nonroad. You can also obtain additional information by contacting Margaret Borushko at:

U.S. Environmental Protection Agency

Office of Transportation and Air Quality

2000 Traverwood Drive

Ann Arbor, MI 48105

borushko.margaret@epa.gov

734-214-4334